Reminds me of that freezing bug with bottom tabs in Vista32, if min tab width was set smaller than 8. Can't remember if it's fixed. Guess tried it last with some 1.6alpha version. And can't remember if the freeze only happened when the tabs row was full and overflowing or not.
And wasn't there some bug with tab close crosses, which only hits if favicons in tabs bar are disabled?
Perhaps this also hits only if bookmark icons are disabled...?